text: Simple organochlorides slowly convert into phosgene when exposed to ultraviolet (UV) irradiation in the presence of oxygen. Before the discovery of the Ozone hole in the late 1970s large quantities of organochlorides were routinely used by industry, which inevitably led to them entering the atmosphere. In the 1970-80s phosgene levels in the troposphere were around 20-30 pptv (peak 60 pptv). However,  these levels had not decreased significantly nearly 30 years later, despite organochloride production becoming restricted under the Montreal Protocol.
  Phosgene in the troposphere can last up to about 70 days and is removed primarily by hydrolysis with ambient humidity or cloudwater. Less than 1% makes it to the stratosphere, where it is expected to have a lifetime of several years, since this layer is much drier and phosgene decomposes slowly through UV photolysis. Consequently, it does play a minor part in ozone depletion.